I. Field
The present disclosure relates generally to communication systems, and more specifically to techniques for receiving a signal in a wireless communication system.
II. Background
Wireless communication systems are widely deployed to provide various communication services such as voice, packet data, video, broadcast, messaging, and so on. These systems may be multiple-access systems capable of supporting communication for multiple users by sharing the available system resources. Examples of such multiple-access systems include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, and Frequency Division Multiple Access (FDMA) systems.
A wireless device (e.g., a cellular phone) in a CDMA system typically employs a rake receiver. The rake receiver includes one or more searchers and multiple finger processors, or fingers. Due to the relatively wide bandwidth of a CDMA signal, a wireless communication channel is assumed to be composed of a finite number of resolvable signal paths, or multipaths. Each multipath is characterized by a particular complex gain and a particular time delay. The searcher(s) search for strong multipaths in a received signal and provide multipaths with signal strength exceeding a particular threshold. The available finger processors are then assigned to the multipaths found by the searcher(s). Each finger processor processes its assigned multipath and provides symbol estimates for that multipath. The symbol estimates from all assigned finger processors are then combined to obtain combined symbol estimates.
The quality of the combined symbol estimates generally improves by processing more multipaths and combining the symbol estimates for all of these multipaths. Thus, each multipath of sufficient signal strength is typically assigned to a finger processor, if available, so that as many multipaths as possible are combined. However, each assigned finger processor consumes battery power. In some applications, it is desirable to conserve battery power as much as possible in order to extend battery life.
There is therefore a need in the art for techniques to efficiently operate a rake receiver to achieve good performance while reducing power consumption.